* new implementation for adjacency list graph
* add example code for undirected graph
* reduce length to 88 columns max to fix build errors7
* fix pre commit issues
* replace print_list method with __str__
* return object in add_edge method to enable fluent syntax
* improve class docstring and include doctests
* add end of file line
* fix pre-commit issues
* remove __str__ method
* trigger build
* Update graph_list.py
* Update graph_list.py
Co-authored-by: gnc <chidieberen1999@gmail.com>
Co-authored-by: Christian Clauss <cclauss@me.com>